Traffic actuated signal system



June 23, 1936. H. A. HAUGH, JR. ET AL 2,045,136

TRAFFIC ACTUATED SIGNAL SYSTEM Filed March 10, 1928 5 Sheets-Shee t l Astreet .5 6t reet 6cm neq H. A. HAUGH, JR 1-: AL 2,045,136

TRAFFIC ACTUATED SIGNAL SYSTEM June 23, {1936.

3 Sheets-Sheet 2 Filed March lo, 1928 was June 23, 1936 H. A. HAUGH. JR,'ET AL 2 045,1 6

TRAFFIC ACTUATED SIGNAL SYSTEM Filed March 10, 1928 5 Sheets-Sheet 3 HMA Haas/1J2. [Hans B 6:52 INVENTORS EUGENE 0 5mm A TTORNEYS.

Patente June 23, 1936 2,045,136 'rnarrro ao'rna'rnn SIGNAL SYSTEM HenryA. Haugh, .lr., Charles D. Geer, and Eugene D. Stirlen, New Haven,Conn., assignors to The Engineering and Research Corporation, New Haven,(John, a corporation of Connecticut I Application March 10, 1928, SerialNo. 260,770

25 Claims. (Cl. 177-337) This invention relates to automatic trafficcontrol systems, and more particularly to a selfregulating signal systemfor controlling vehicle traffic at intersections of very busy streets incongested down-town areas of cities.

One form of automatic control system to which this invention may beapplied is set forth in British Patent No. 299,040 and relates to atranic signal system in which the signal is operated through acontroller by means of traffic moving in the street. In this system thetrafiic is regulated at each intersection by vehicle-actuated meanslocated near the intersection.

aforesaid Haugh application, Serial No. 227,490

have a common assignee. v

. One object of this invention is to provide apparatus which may be usedin conjunction with an automatic tralfic control system such as that setforth, whereby the system shall be more fiexible in operation and shallhave a wider range of application, and this object is accomplished byproviding apparatus which shall function in response to the volume oftrafiic moving on the highway at a distance from the intersection.

Another object of this invention is to provide a variable 'time limitrelay mechanism which shall operate in conjunction with-automaticvehicle actuated systems now in use, to control the period of time whichtraffic shall wait on one cross street before the signal is taken awayfrom continuous traflic to allow waiting vehicles on the intersectingstreet to proceed.

A further object of the invention is to provide variable time limitrelays for use in highway traffic control systems of the characterdesignated, the time limits of which shall be varied by vehiculartraffic at a distance from the intersection, so that the signal fortraffic to proceed shall be given through variable maximum periods oftime, depending upon the volume and/or density of traliic in thehighways.

A further object of the invention is to provide variable maximum timelimit relays for traffic control systems of the character designated inwhich the maximum timeperiodat which the relays operate shall be in parta-function of the volume and/or density of trafiic on the streetsleading to the intersection.

Other objects will be more manifest by reference to the followingspecification and drawings and as particularly set forth in the claims.

In the drawings Figure 1 is a diagrammatic view of a tramc signal systemembodying our invention.

Figure 2 is a diagrammatic drawing of one embodiment of our inventionshowing in detail the electrical circuits and various components.

Figure 3 shows in diagram form a vehicle actuated means for completingan electrical circuit and subsequently breaking it as the wheel of a 7car passes over it.

control system. An automatic trafiic control system embodying ourinvention comprises three parts: 1. Any automatic trafiic control systememploying a relay or timer system to control the operation of the.signal means; 2. A variable time limit control device having a minimumand a maximum period which can be set arbitrarily for any predeterminedtime and arranged so that its time of operation will vary between thesetwo set arbitrary periods in accordance with impulses received; 3. Tramcactuated means placed in the streets which pass through the intersectionon which the signal means is used, but placed at a'distance from theintersection. In practice we contemplate placing these street devices inthe streets at the intersections adjacent to the intersection on whichthe signal is placed.

While we have described above in general an improvement on an automatictramc control system embodying our invention, and have shown that thisinvention is comprised of three main and interconnected parts, we nowdescribe in detail one complete and specific system embodying ourinvention. In this specific and complete embodiment of our invention, weillustrate the device used in conjunction with an automatic trafficcontrol system such as set forth in the British Patent No. 299,040 abovereferred to. We do not describe in detail all of the features of .theoperation and construction of the system shown in the Brit'- ish patentreferred to except in so far as to show its relation to this embodimentof our invention. The system shown in the British patentreferred to asone embodiment of our invention is capable of numerous methods ofoperation as described in the specification of the patent under theseveral connections and combinations of connections. and it is clearthat our invention may be applied to any one or more of the Britishsystems of operation, regardless of whether the trafilc actuated meansshown in the British patent are connected or disconnected under any ofthe modes of operation so long as the maximum limit relays 28 and I3 inour application, or their equivalent in the British patent referred to,are a governing factor in the timing.

InFigure l, the elements I. 2, 3, 4, 5 and 8 represent the units of anautomatic traffic control system to which our invention may be applied.I is a signal means, 2 is the controller, 3, 4, 5 and 8 are vehicleactuated means used to affect the operation of the controller. I, 8, 8and III are vehicle actuated means located at a distance from theintersection and employed to control the operation of the variable timelimit relays called for by our invention. The wiring will be fullyexplained by reference to the other figures.

Figure 3 shows a vehicle actuated means consisting of a ramp arm I!pivoted at I8, and supported by spring I9. When a wheel passes over theramp arm it is depressed, pressing contacts I5 and I6 together closingthe circuit in wires I I and I2. When the wheel has passed oil of theramp am, spring I9 again raises the arm, allowing contacts I6 and I6 toseparate and open the circuit in wires II and I2.

Figure 4 shows in further detail the method of wiring the vehicleactuated means together.

Figure 2 shows the wiring in further detail, and the construction andfunction of the variable time limit relays in diagram form. The variabletime limit relays are designated in 58 and SI. They are constructed asfollows: 28 is a solenoid. 2I is the solenoid, core, and is movable. 23is a cylinder containing all and 22 is a piston containing a valve whichwill allow rapid downward motion, but a slow restricted upward motion.This construction is the same as in the usual oil dash pot" time limitrelay known to the arts. When 28 is energized, the core 2| rises slowlyagainst the resistance of the dash pot in the well-known manner. When 28is de-energized the core drops back at once. Contacts 51 and 58 whichare opened by rod 24 when core 2I has risen sufficiently to allow it topress against 42 are attached to an insulated block H, which is in turnattached to a movable rod 25. This movable rod 25 has ratchet teethalong its lower end as illustrated. Adjacent to the ratchet is a magnet28 whose armature 21, rests against stop 31. Armature 21 is arranged sothat when magnet 26 is energized, the ratchet teeth are engaged and theratchet is lifted one tooth. Magnet 29 is connected so as to beenergized wheneversolenoid20isenergized. Attached to armature 34 ofmagnet 29 is a magnet 28 and its armature.

38. Armature 34 is pivoted at", and is held against stop 38 by spring35. When 29 is not energized armature 30 of magnet 28 is disengaged fromthe ratchet on arm 25. When magnet 29 is energized, armature 34 pullsover to the magnet, and the pivot 43 causes the lower end of the ar-'which is pivoted at the point 3i is kept against stop 44 by spring 36and pawl or check 33 engages the teeth of theratchet while the point ofarmature 38 does not. By the construction of the check as illustrated,the ratchet can be raised, inasmuch as the check will not prevent upwardmotion. but the ratchet cannot fall. On the other hand. if magnet 28 isenergized while magnet 29 is energized, the pointed end of armature 38will move toward the ratchet, while the check 33 will 10 move awayslightly. The construction as illus trated is such that energizingmagnet 28 and then de-energizing it will lower the ratchet one tooth.When magnet 29 is energized," and magnet 28 is I not energized, ifmagnet 28 is energized it willlift 15 its armature 21 which will raisethe ratchet one tooth. The check 33 will allow this to occur, butprevent the ratchet from falling back upon the-deenergizing of 26.

Thus it is clear that when 29 is energized, every 20 time the circuit to28 is made and broken, the

,ratchet will rise one tooth, and every time the circuit to 28 is madeand then broken, the ratchet will fall one tooth. Stops 38 and 48 areadjustable and represent the maximum that the ratchet 25 can riseor'fall.

In this time limit relay, the time at which contacts 51 and 58 areseparated after energizing of solenoid 28 will depend upon the positionof the arm bearing the contacts and the ratchet. If 30.

the arm is near or at stop 40 the period will be short-if the arm isnear or at stop 39 the period will be long. The position of the arm willdepend upon the relative number of impulses received by the two magnets26 and 28. 35

Referring to Fig. 5, the following description illustrates our inventionas applied to the automatic control system set forth in the BritishPatent No. 299,040 referred to, above. To more clearly explain theoperation of this system we 40 will first describe it withoutconsidering the modifying action of our invention. To do this we willtemporarily disregard ramps I, 8, 9, and I0, shown in Figure '1 andtheir effect on variable time limit relays 68 and 5|. We shall alsoassume that coil 5 28 will require 30 seconds, continuous energizing,before it breaks contacts 51 and 68.

Referring to Figures 2 and 5 of the drawings, the wiring diagram showsthe connections arranged for the operation of the system when the 50yellow light is visible from both streets in the absence of traffic oneither street.

Case ISinqle vehicle approaching from A Street-Assume a vehicleapproaches on A Street and actuates ramp 5, as shown in Figure l, clos-5.3 ing the circuit between wires'8l and 82. This energizes coil I92through wires 62 and 6|, coil I82 and wire 248, pulling up armature I9I,breaking the circuit between armature I 9| and contact I98 and closingthe circuit between armature Hi 00 and contact I93. This allows currentfrom a suitable source to flow through relay I26 by way of wires III,IIIl,2III and 2 thereby operating armatures I45 and I49. The contact ofarmature I45 with contact I48 causes current to continue 5 to flowthrough relay I28, by way of wires 2I2, contact I8I, armature I59, wires228, 222 and 22I, thus holding relay I28 in the operated position afterthe passing of the wheel has permitted contacts I9I and I93 to separate.Armature I49 7 makes contact with I50, by way of wires 2", M8, armatureI98, contact I99, wire 2I9, relay I34 and wire 228, armature I85 beingalready in contact with I81, thereby causing armature I" to breakcontact I18 and make contact I18. Current being ture I65 breaks fromcontact I61 thereby interinterrupted'between armature I11 and contactI19 de-energi'zes relay I33, which was energized through wires TM, 222,armature I11, contact I19, wire 221, wires I51, I58, contacts I63 andI62, wire 223 and wire 2I6. This causes armature I68 to break fromcontact I10 thereby preventing energization of relay I35 and action ofthe latter through armature I14 and contact I16 to light the green lighton B Street and the red light on A Street. Armature I68 making contactwith I69 causes current to flow through wire 224 and solenoid 20 andrelay I30. Solenoid 20 and relay I30 thereupon begin to operate. If noother car 'approaches from A Street to connect wires 6| and 62 and thusseparate contacts I90 and I9I shown in Fig. 5, relay I30 is continuouslyenergized. 10 seconds after relay I30 is energized, armature I59 breaksfrom contacts I and I6I thereby stopping the flow of current by way ofwires 2I0, armature I45, contact I46, wire 2I2,

contact I6I, contact I60, wire 2I3, contacts 51 and 58 and wire 2M,through relay I32 which permits armature I to break from contact I61 andmake contact with I66 thereby de-energizing relay I34 and through wire225 energizing relays 13 and I3I causing armature I" to break fromcontact I13 and make contact with I12, thereby extinguishing green lightand red light 86 and lighting the yellow light 89. When relay I34 isde-energized, armature I11 breaks from contact I18 and makes contactwith I19. Breaking contact I18 opens the holding circuit and releasesthe armature of relay I26, thus dropping it back to its normalunoperated position. Armature I11 making contact with I19 energizesrelay I33. Two seconds after relay I33 is energized, armature I68 breaksfrom contact I69 thereby deenergizing solenoid 20 and relay I30 andmakes contact I10. The de-energizing of solenoid 20 has no effect on thecircuit inasmuch as it had not been energized continuously for 30seconds. The release of relay I30 causes armature I59 to make contactwith I60 and I6I thereby energizing relay I32, from wire 226 which,after 2 seconds, causes armature I65 to break from contact I66 therebyde-energizing solenoid 13 and relay I3I and make contact with I61. ofsolenoid 13 and relay I3I has no effect on the circuit, inasmuch asneither had been energized long enough to operate. A yellow light is nowshown in both streets and the entire system hasreturned to its originalcondition.

Case II--Continuous tralfic on A Street with no trafllc on B Street.Ifin the preceding operation no cars had approached the intersection fromBStreet, but vehicles had approached on A Street and actuatedv ramp 5 or1 within 10 seconds of the previous actuation of either ramp,

thereby breaking the coil circuit of 10 second relay I30 at contacts Iand I9I, shown in Fig. 5, then armature I59 would have maintained acontinuous contact with I60 and I6I, thus preventing 10 second relay I30from causing the circuit to operate as in Case I so as to extinguishgreen light 85 showing in A Street and red light 86 showing in B Street.This circuit provides in addition, that current flow through the coil ofrelay I26, armature I45 and contact I46 even after armature I11 hasbroken contact from I18. The purpose of this is brought out later. The30 second time-limit relay 20 which was energized at the same time .that10 second relay I30 was energized, breaks the circuit between contact 51and contact 58 30 seconds after it is energized, thereby releasing the 2second time limit relay I32. Arma The de-energizing rupting the currentoperating relay I34. Armature I1I breaks contact from I13 and makescontact with I12 thereby extinguishing green, light 85 showing in AStreet and redlight 86 showing in B Street, and lighting the yellowlight 80.

Armature I11 breaks from contact I18 but in this particular case doesnot interrupt the current operating relay I26 because of the fact thatsaid current is supplied through contacts I59 and I 6I on relay I30which are connected in parallel with contacts I11 and I18. The fact thatrelay I26 therefore remains energized, causes lights 85 and 86 to showafter yellow light 89 has been lighted for 4'seconds, thus returning theright of way to A Street after giving pedestrians a 4 second period inwhich to cross A Street.

The actual operation of the circuit to produce this effect is asfollows. Armature I11 connects with contact I 19, thereby energizing the2 second time limit relay I 33 as before described. Two seconds afterrelay I33 is energized armature I68 breaks from contact I69 therebyopening the circuit to solenoid 20 and relay I30, through wire 224,

whereupon contact 51makes contact with 58 and energizes the 2 secondrelay I32. Two seconds after relay I32 is energized, armature I65 makescontact with I61, thereby energizing relay I34 whereupon armature I1Ibreaks from contact I12 thus extinguishing the yellow light and makescontactwith I13 thus lighting the A Street green light 85 and the BStreet red light 06. This cycle-of operations repeats as long asvehicles operate either ramp in A Street within intervals of 10 secondsand none operate a ramp in B street. In the event that vehicles fail tooperate either A Street rampwithin an interval of 10 seconds, thesubsequent operation is as described in Case I.

Case III--One vehicle on A Street followed within 10 seconds by onevehicle on B Street.-

Under this condition, the circuit operates as in Case I with thefollowing changes. When relay I34 is de-energized through the breakingof armature I65 from contact I61, armature I11 makes contact with I 19.A vehicle operates either ramp 4 or 6 in B Street which causes currentto flow through the coil of relay I21. The contacts of ramps 4 and 6 asshown in the drawings, control relay I21 through wires 63 and 64 andrelay I94 just as contacts in ramps 5 and 3 control relay I26, and theycontrol relay I3I just as contacts in ramps 5 and 3 control relay I30.Relay I21 is now held in the operated position by current flowingthrough armature I41 and contact-I48,

contact I64 and armature I62, and wires 223 and 2I6. Armature I11 makingcontact with I19 energizes relay I 33 through wires I51, I58 contactsI63, and I62. Two seconds after relay I33 is energized, armature I68makes contact with I10 thereby operating relay I35 through switch 206,

yellow light and to make contact with I16 thereby lighting the greenlight 83 on B Street and red light 84 on A Street. Thus the effect hasbeen that the vehicle in A Street has retained the right of way for 10seconds and at the end of this 10 second period, the signal has gonethrough the cautionary yellow period to an indication of right of way onB Street.

When relay I35 was energized I80- I gized aiterarmature I58 has madecontact with I60 and I6I. When relay I32 was originally deenergized bythe separation of armature I58 irom contact I60, as explained in Case I,armature I65 made contact with I66 thereby energizing time limit relays13 and I3I. relay I 3| was energized, due to the fact that neither rampin B Street had been operated by a second vehicle, which would havede-energized relay I3I, armature I62 breaks contact with I63 and I64thereby de energizing relay I33 thus permitting armature I68 to breakcontact'Irom I 10 and make contact with I68. The breaking of the circuitbetween I68 and I10 de-energized relay I35, thus breaking contactbetween I14 and I16 thereby extinguishing green light 83 and red light84 and making contact between I14 and I thus lighting the yellow light88. Armature I80 breaks from contact I8I thereby de-ener gizing relayI21 by way of wires 230 and 23I, whereupon armature I41 breaks contactwith I48. Armature I80 in making contact with I 82 energizes the 2second relay I32 through contacts 51, 58, I60 and I58, on relays andI30. Two seconds after relay I32 is energized armature I65 makes contactI61 .and breaks from contact I66 thereby de-energizing time limit relays13 and I3I. Inasmuch as relay 13 had not been energized for a suflicient.length of time to operate its armature, it has not acted to control thecircuit. The de-energizing of relay I3I permits ar-' mature I62 to makecontact with I63 and I64 thereby energizing. relay I33,'through contactsI18 and I18. Two seconds after relay I33 is energized, armature I68breaks from I68 thereby deencrgizing relays 20 and I30 and makes contactwith I10 so that relay I35 operates immediately when relay I21 isenergized. The circuit has now completed its cycle and has returned tothe condition at the beginning of Case I, and as shown in Fig. 2.

Case IV-Continuous traflic on A Street with one vehicle waiting on BStreet-Under these conditions, the circuit operates as outlined in CaseII until a vehicle operates one of the ramps in B Street. The opening ofthe circuit between contacts 51 and 58 which occurs 30 seconds afterrelay 20 isenergized, deenergizes relay I32 causing armature I65 tobreak from contact I61 and make contact with I66. Connecting armatureI65 with contact I66 energizes relays 13 and 13I. Breaking the circuitbetween armature I65 and contact I61 de-energizes relay I 34 whereuponarmatures HI and I11 fall back extinguishing the A Street green light 85and the B Street red light 86 through breaking the circuit betweenarmature Ill and contact I13. Armature I1I making contact with I12lights the yellow light 89. Armature I11 breaking from contast I18 doesnot de-energize relay I26 because current for relay I26 is suppliedthrough wire 225, armature I58 and contact I 6I, armature I45 andcontact I46. In the meantime a vehicle has operated one of the ramps onB Street cnergizingrelay I21. Current to keep relay I21 energized aftersaid vehicle has crossed the ramp flows through armature I41, contactI48, contact I64, and armature I62. Armature I52 now makes contact withcontact I53. Armature I11 which made contact with Ten secondsaftercontact with I63.

contact I18 when relay I 34 was de-energised thereupon energized relayI33 through wires I51 and I58, contacts I63 and I62. Two seconds afterrelay I33 is energized armature I58 breaks from contact I68 therebyde-energizing relays 28 5 and I30. Armature I68, through making contactwith contact I10, now energizes relay I35 through switch 206 andcontacts'20l, 200, I53, and I52. Armature I14 now breaks from contactI15, thus extinguishing the yellow light, and makes contact with I16,thereby lighting the B Street green light 83 and the A Street red light84. Armature I80 breaks from contact I 82 and makes contact with I8Ithereby causing relay I32 to remain deenergized despite the closing ofcontact 51 with in contact 58. Armature I65 therefore remains in contactwith I66 keeping relay 13 energized and also relay I 3i .energized,inasmuch as this case assumes that a second car does not pass over a BStreet ramp. Hence 10 seconds after relay III was energized, armatureI62 breaks from contact I63 and contact I64 thereby de-energizes relayI33. Armature I68, of relay I33, now breaks from contact I10 and makescontact with I88 thereby energizing relays 20 and I30. Relay I35 is nowde-energized through the break between armature I68 and contact I10.Armature I14 now breaks from contact I16 thereby extinguishing the BStreet green'light 83 and the A- Street red light 84. The yellow light88 is now lighted through armature I14 and contact I15. Armature I80 atthe same time breaks from contact I8I thereby de-energizing relay I 21inasmuch as armature I62 is not now in contact with I64.

Armature I80 makes contact with contact I82 thereby energizing relay I32through contacts 51, 58, I58, and I60. Two seconds after relay I32 isenergized, armature I65 breaks from contact I66, thereby de-energizingrelay 13 and relay I3I, and makes contact with I61, thereby energizingrelay I34 through switch 205, contacts I88, I88, wires 2I8 and 2",contacts I50 and I48. Armature "I now breaks from contact I12extinguishing the yellow light and makes contact with I13 again lightingthe A Street green light 85 and the B Street red light 86. Armature I11also breaks from contact I18 thereby insuring that relay I33 will remainde-energized even though wire I51 be in contact with wire I58 andarmature I62 be in Armature I11 now makes contact with I18 thusparalleling armature I58 and contact I6I. The system has now returned tothe condition in which it was when the single vehicle actuated the rampin B Street. In this description we have shown how continuous trailic inA Street would be interrupted for a suiiicient period to allow a singlevehicle from B Street to use the intersection, and how right of waywould return immediately thereafter to A Street in which the continuousstream of traflic had 60 been interrupted.

Case V-C'ontinuous tramc in both streets.- Under these conditions thecircuit operates asit did in Case II to transfer the right of way from AStreet to B Street. But, continuous trafllc in B Street opens thecontacts through which the current energizing relay I3I passes. ArmatureI62 therefore continues to make contact with I63 and I64. Relay I33therefore remains energized until wire I51 breaks from wire I58 whichwill take place 30 seconds aiter relay 13 is energized. The energizingof relay 13 is caused in accordance with the description given in CaseII. Wire I51 now breaking contact with I 58 de-energizes relay I33.Armature I68 breaks contact from I18 2,045,186 and makes contact withI69 thereby de-energizing relay I and energizing time limit relays 20and I30. Armature I16 now breaks contact with I16, therebyextinguishingBStreet green go" signal 83 and A Street red light 84, andmakes contact with I15 thereby lighting the yellow light. Armature I80now breaks from contact I8I which action has no effect on the circuitinasmuch as this connection is also made by armature I62 and contactI56. Armature I80 makes contact with I82 thereby energizing relay I32.Two seconds after relay I32 is energized, armature I65 breaks fromcontact I66 thereby causing the de-energizing of relays 13 and I3Ithereby causing wire I51 to make contact with I56 and makes contact withIE1 thereby energizing relay I3t through switch 205, contacts I99, I90,I and I49. Armature I1I now breaks from contact I12 extinguishing theyellow light and makes contact with I13 lighting the A Street greenlight 85 and the B Street red light 86. Armature I11 breaks from contactI19 thereby causing relay I33 to remain ole-energized even though wireI51 makes contact with M8 and armature I62 makes contact with I63.Armature I11 now makes contact with I18 and the circuit has returned tothe condition in which it was at the beginning of this description.

It is apparent from the foregoing description that the relay 20 limitsthe length of time during which tralfic may flow continuouslyon AStreet. As soon as the go signal is given to A Street, relay 20 isenergized and if trafiic is continuous on A Street the go signal remainson A Street for 30 seconds. Then relay 20 operates so as to remove thego signal from A Street and give it to B Street. Simultaneously relay 20is de-energized and relay 13 is energized. Relay 13 performs the samefunctions for B Street as relay 20 does for A Street.

Nevertheless the maximum period during which traffic may flowundisturbed is fixed and cannot be varied by the traffic. The purpose ofour invention is to vary-this maximum period by electrical impulsescaused by traffic operating vehicle actuated devices in the streets. Themethod of obtaining this variation and the value is set forth below.

While in the above description the application of our invention to oneform of trafilc control systems has been set forth and one embodiment ofour invention has been illustrated, it will be obvious to those skilledin the art that the in-- vention may take many forms and may be appliedto many types of traflic control systems, and it is not intended tolimit our invention to the particular form illustrated. It will beappreciated that numerous changes in construction and rearrangement ofparts with respect to the construction of the timer,-of the timeadjustment means, of the traffic responsive means, and in the mode ofinstallation and point of application of these several means might beresorted to without departing from the spirit of the invention asdefined by the claims.

A Street, vehicle actuated means 1 and 9 are connected in parallel bywires II and I2. Vehicle actuated means 8 and I0 are connected inparallel by wires I3 and I4. Variable time limit relay 50 functions tocontrol the maximum period through which a continuous stream of trafficcan hold the go signal on A Street. nected to magnet '26 in relay 50 andto magnet H in relay 5I. Street, solenoid 20 will immediately beenergized Wires II and I2 are con-- When the go signal is given to A andfunctions as heretofore described. Magnet 29 will be energizedsimultaneously inasmuch as in our invention this magnet is connected inparallel with the solenoid. Also since B Street has the stop signal,solenoid 13 will be deenergized as heretofore described Since magnet 12is in parallel with solenoid 13, it will also be de-energized. When thego signal is on A Street, ve=

hicles moving toward the intersection on A Street will pass over ramp1-or ramp 9, and will send electrical impulses through wires II and I2to variable time limit relays 50 and 5I. Impulses going into variabletime limit relay 50 through wires II and I2 operate magnet 26 causingratchet 25 to raise, and since A Street has the go signal, solenoid 20,and magnet 29 are energized, so that ,when magnet 26 causes the ratchet25 to be raised, pawl 33 will prevent its return. Since ratchet 25 hasbeen raised, rod 24 has to move through a greater distance than formerlybefore it separates contacts 51 and 58 and this allows solenoid 20 to beenergized for a longer period than 30 seconds. Impulses going tovariable time limit relay 5| through wires I I and I2 energize magnet II Since B Street has the stop signal,

solenoid 13 and magnet 12 are de-energized, and

the ratchet will not operate, but remains in its minimum time position.Thus the true efiect of cars arriving on A Street during the periodwhich it holds the go signal is to increase the length of, the maximumperiod for which A Street can hold the go.signal. Cars approaching on BStreet pass over vehicle actuated means 8 and I0, and send electricalimpulses through wires I3 and I4 to variable time limit relays 50 and5|. Impulses going to relay 50 through wires I3 and I l energize magnet26 causing ratchet to drop one tooth for each impulse. Impulses going torelay 5| through wires I3 and I4 energize magnet 10. Inasmuch assolenoid 13 and magnet 12 of time limit relay 5| are not energized,there is no effect producedin time limit relay 5|. Hence, when A Streethas the go signal, cars approaching the intersection on A Street tend tolengthen the maximum period during which A Street can 7 hold the "go.signal, while cars approaching on A Street tend to shorten the periodduring which B Street can hold the go signal.

The result of this operation is as follows. Suppose both streets have amore or less continuous tramc flow, but, A Street has a fairly denseflow while B Street hasa sparse and scattered flow, and suppose the go"signal is on A Street. As the vehicles on A Street approach the intersection, magnet 26 willbe operated very frequently by the passage of thelarge number of vehicles over ramps 1 and 9. Vehicles approaching theintersection on B Street, will pass over ramps 8 or I0, energizingmagnet 28 from time to time.

The vehicles will move forward intothe block and stop at A Street. Sincethere are many more somewhere near the maximum period. when A Streetloses the'light, name on A Street will be in the least congestedcondition since it has been flowing freely, barring some other.conges- 7name on B'Street will be condensed into a waiting block. when B Streettraflic moves forward, any new cars arriving on B Street will tend tolengthen the B Street maximum period as determined by relay 13, whilecars moving into the waiting block on A Street will tend to shorten theB Street go; period. Since there is not a dense flow on B Street themaximum period, as determined by relay I3, will be shortened so as toalmost coincide with the minimum period as determined by relay l3! and BStreet will lose the "go signal at, or shortly after, the expiration oftheminimum period. It the trafiic on both streets becomes about equal,and is light in volume, streets A and B will alternately hold the gosignal for equal minimum or nearly equal minimum periods, giving afrequent shifting oi the go signal back and forth between the streets.It trafllc becomes unbalanced between the two streets the maximumperiods will lengthen out on the street having the heavier tramc flow.It traiflc on both streets increases to a degree of congestion, the

periods will lengthen on both streets, for cars moving on the "go streetwill increase its period, while on the stop" street, congestion willprevent cars coming into the block and thus prevent a decrease in the gostreet's time period. This is especially desirable for it is believed bysome traflic engineers that where traflic is especially dense long go"periods are the most eflicient,'whereas in light traihc short go"periods are more desirable.

What we claim is:

1. In a traffic control system, a signal device for intersecting trafliclanes for indicating stop and go signals, vehicle actuated means locatedin the traillc lanes and at a distance from the intersection, a controlmechanism connected to said vehicle-actuated means for regulating thedisplay oi signals alternately to the trafllc lanes including automaticvariable maximum time limit relay means for determining the maximumperiod of said displays, said relay means being actuated by the vehiclemeans in such a manner that traino moving in the traflic lanes shallvary the maximum period as determined by said maximum time limit relaymeans and during which a go? signal may be displayed to one 01 the laneswhile trailic is accumulating in an intersecting lane.

2. In a tramc signal control system for intersecting tramc lanes, asignal device to be disposed at the intersection of the lanes, vehicleactuated means located in or adjacent to the trailic lanes near theintersection, other vehicle actuated means placed in or adjacent to thetrailic lanes at a distance from the intersection; a control mechanismconnected to said vehicle actuated means for operating the signal deviceto display "go" signals alternately to the said lanes in response toimpulses received from both of the vehicle actuated means and includingautomatic variable time limit relay means which determine the maximumperiod of said displays, said relay means being operated by the vehicleactuated means in such a manner that tramc moving in the tramc lanesshall influence the period as determined by said maximum time limitrelay tion in the path of the trafllc moving on A Street:

of way periods to each lane, means operable to limit the time of rightof way in each lane and vehicle actuated means for varying the limitingpoint of the limiting means on the right of way period in response tochanges in the diiierence between the number of cars traversingeachlane.

4. A traiilc control system to be disposed at the intersection of twovehicle lanes, and including signalling means for according andinterrupting right of way indication to each lane, operating means forsaid signalling means, vehicle actuated means disposed in at least oneof said lanes for controlling said operating means to cause saidsignalling means to indicate right of way to said lane, means forming apart of said operating means to limit the time period of right of way ineach lane and other vehicle actuated means for varying the time periodof said right of way limiting means in response to changes in thedifference between the number of cars traversing each lane.

lane, means forming a part of said operating.

means to limit the time period of right of way in each lane and othervehicle actuated means in at least one lane and disposed'at a pointfurther from the intersection than the first named vehicle actuatingmeans, said last named means being operable during the right of wayperiod of said lane to increase the time period of said right of waylimiting means.

6. A traflic control system to be disposed at the intersection of twovehicle lanes, and including signalling means for according andinterrupting right of way indication ,to each lane, operating means forsaid signalling means, vehicle actuated means disposed in at least oneof said lanes for controlling said operating'means to cause saidsignalling means to indicate right of way to said lane, means forming apart of said operating means to limit the time period of right of way ineach lane, and other vehicle actuated means in at least one lane andlocated at a point fur.- ther from the intersection than the first namedvehicle actuating means, said last mentioned means being operable duringthe right of way period of the other lane to decrease the time period ofsaid right oi way limiting means.

7. A trailic control system to be disposed at the intersection of twovehicle lanes, and including signalling means for according andinterrupting right of way indication to each lane, operating means forsaid signalling means, vehicle actuated means disposed in at least one01' said lanes for controlling said operating means to cause saidsignalling means to indicate right of way to said lane, means forming apart 0! said operating means to limit the time period of right of way ineach lane and other vehicle actuated means in at least one lane andlocated at a point further from the intersection than the first namedvehicle actuating means, said last named means being connected to saidoperating means to increase the time period of said right oi waylimiting means during the right of way oi said lane and to decrease thetime period of said right of way limiting means during right of way tothe other lane.

8. A trafllc control system to be disposed at the intersection of aplurality of interfering traiiic each of said lanes, traflic actuatedmeans disposed lanes, comprising "stop and go indicators in each of saidlanes, traflic actuated means disposed in at least one of said lanes andconnected to said indicators'to cause the display of a go signal in saidlane upon actuation by an approaching vehicle, means associatedtherewith for retaining said go signal for a predetermined period oftime, and means for varying said predetermined period of time inresponse to changes in the ratio that the number of cars traversing saidlast mentioned lane bears to the number of cars traversing aninterfering lane.

9. A trailic control system to be disposed at the intersection of aplurality of interfering trailic lanes, comprising stop and"goindicators in in at least one of said lanes and connected to saidindicators to cause the display of a go signal in said lane uponactuation by an approaching vehicle, means associated therewith forretaining said go signal for a predetermined minimum period of time,means for retaining said go signal beyond the predetermined minimumperiod of time upon the subsequent actuation of said first mentionedmeans, means for terminating the display of said go signal upon theelapse of a predetermined maximum period of time and means for varyingthe predetermined maximum period of time in response to changes in thedifference between the number of cars traversing each of said lanes.

10. A traflic control system to be disposed at the intersection of aplurality of interfering traffic lanes, comprising stop and govindicators in each of said lanes, traffic actuated means disposed ineach of said lanes, means connected to said trafilc actuated means andsaid indicators for causing the display of a go signal in a lane uponoperation of the traflic actuated means in said lane, means associatedtherewith for retaining said go" signal in saidlane for a predeterminedminimum period of time, means for retaining said go signal in said lanebeyond said predetermined minimum period of time upon the subsequentactuation of the trafiic actuated means disposed in said lane, means forterminating the display .of said "go signal upon the elapse of apredetermined maximum period of time, and additional trafiic actuatedmeans disposed in each of said lanes for varying the length of thepredetermined maximum-period of time in response to changes in thecomparative density of traffic in said lanes. i

11. A traffic control system to be disposed at the intersection of twovehicle lanes including signalling means for according and interruptingright of way in each lane, trafiic actuated means in at least one ofsaid lanes and connected to said signalling means for according right ofway indication to said lane when actuated by an approaching vehicle, aminimum time control device associated therewith for retaining right ofway in said lane for a predetermined period, means for retaining saidright of way beyond said period upon r the subsequent actuation of saidtraific actuated 'means, a variable maximum time control device forinterrupting said right of way, and other traffic actuated means forvarying the period of operation of said variable maximum time controldevice. i

12. A traflic control system to be disposed at the intersection of twovehicle lanes including signalling means for according and interruptingright of way in each lane, traific actuated means in at least one ofsaid lanes and connected to said signalling means for according right ofway indication to said lane, a minimum time control device associatedtherewith for retaining right of way 1 maximum time control device.

13. A traffic control system to be disposed at the intersection of twovehicle lanes including signalling means for according and interruptingright of way in each lane, trafiic actuated means in one of said lanesand connected to said signalling means for according right of wayindication to said lane, a minimum time control device associatedtherewith for retaining right of way in said lane for a predeterminedperiod, means connected to said trafilc actuated means for retainingsaid right of way beyond said period upon the continued approach of.vehicles, a variable maximum time control device for interrupting saidright of way after the'elapse of a predetermined period of time, andother trafiic control means located in the other of said trafiic lanes,said last named means being operable during the right of way ofinterfering traffic lanes, signalling means for according andinterrupting right of way to each lane, timing mechanism connectedthereto for causing the alternate display of said signalling means ineach lane for predetermined periods of time, and means associatedtherewith for varying the predetermined periods of time in response tochanges in thedifierence between the number of cars in each lane.

15. In combination with a traflic control system adapted to be disposedat the intersection of interfering traific lanes, signalling means foraccording and interrupting right of way to each lane, timing mechanismconnected thereto for causing the alternate display of said signallingmeans in each lane for predetermined periods of time, and means forvarying the predetermined periods of time in response to changes in thedifference between the number of cars in each lane, said last namedmeans including traffic actuated devices disposed in each lane forincreasing the period of right of way accorded that lane when actuatedduring the period of rightof Way in said lane and for decreasing theperiod of right of way accorded an interfering lane when actuated duringthe period of right of way in said interfering lane.

16. A trafiic control system, to be disposed at the intersection of aplurality of trafilc lanes, comprising signalling means for alternatelydisplaying stop and right of way indications in each lane, timing meansconnected thereto for controlling the period of right of way accordedswitch mechanism after the elapse of a predctermined period of time,magnetically operated means for decreasing said predetermined period oftime when energized, vehicle actuated devices disposed in a lane nothaving the right of way and connected to said magnetically operatedmeans to energize it upon a vehicle actuating the vehicle actuateddevice in last said lane, other magnetically operated means forincreasing said.

predetermined period of time when energized, and other vehicle actuateddevices disposed in the trafiic lane having the period of right of wayand connected to said last named magneticaily operated means to energizeit upon the approach of a vehicle in said lane.

17. A trafiic control system to be disposed at the intersection of twotraihc lanes and comprising signalling means adapted to accord andinterrupt right of way to such lanes, trafilc responsive meansassociated with one of said lanes. a timer connected between saidtraflic responsive means and said signalling means and including meansacting in response to trafllc actuation of said responsive means foraccording and maintaining right of way in said one lane betweenpredetermined minimum and maximum periods, further trafiic responsivemeans in the second lane and means for reducing said maximum period inresponse to actuation of said further trafiic responsive means in thesecond lane when the first lane has the right of way.

18. A tramc control system to be disposed at the intersection of twotraffic lanes and comprising signalling means adapted to accord andinterrupt right of way to such lanes, traflic responsive meansassociated with one of said lanes, a timer connected between said 'tramcresponsive means and said signalling means and including mechanismacting in response to actuation of said responsive means to accord andmaintain right of way in said lane up to a predetermined maximum periodof time, further trafllc responsive means in the second lane and meansfor reducing such maximum time period in response to operation of thefurther trafiic responsive means in the second lane when the first lanehas the right of way.

19. A traflic control system to be disposed at the intersection of twotramc lanes and comprising signalling means adapted to accord andinterrupt right of way to such lanes, traflic responsive meansassociated with each of said lanes, a timer connected between saidcontrols and said signalling means and including means acting inresponse to actuation of said responsive means for according andmaintaining such right of way alternately in each lane for a minimumperiod of time, means for increasing the period of right of way beyondsaid minimum period in response to operationof said traflic responsivemeans in the lane having'right of way, means for interrupting said rightof way after a predetermined maximum period of time, and means fordecreasing said maximum-period on the lane having the right of way inresponse to actuation of traiiic responsive means in the lane nothavsivemeans in one of said lanes, timing means connected to thesignalling means and traflic responsive means and including meansoperable upon actuation of the responsive means to accord right of waytosaid lane up to a predetermined maximum period, and means operable inresponse to actuation at a remote intersection of interfering trafliclanes including one lane common to the first and second mentionedintersections to vary said maximum period. 21. A trafiic control systemincluding at' one intersection of interfering traflic lanes signallingmeans for according and interrupting right of way in the lanes, trafilcactuated means in 'the lanes of said intersection, operating means con-10 nected to said signalling means and traillc lectu- .ated means tocause said signalling means to transfer right of way back and forthbetween the lanes in response to actuations of said trafllc actuatedmeans, timing means associated with said operating means to provide timelimits for the period of right of way accorded to such lanes and traificresponsive means located at a second intersection of trafilc lanesincluding one lane common to both mentioned intersections, and meansassociated with said timing means and connected to said trailicresponsive means and operable by actuation of said traillc responsivemeans at said second intersection to vary the time limit of said timingmeans. 22. A traffic control system including at one intersection ofinterfering traific lanes signalling means for according andinterrupting right of way in the lanes, trailic actuated means in thelanes of said intersection, operating means connected to said signallingmeans and trafllc actuated meansto cause said signalling means totransfer right of way back and forth between the lanes in response toactuations of said traflic actuated means, timing means associated withsaid operat- 3 ing means to provide time limits for the period of aright of way accorded to such lanes and including traflic responsivemeans located at adjacent intersections of. trafilc lanes, eachincluding one lane common with the first mentioned intersection, andmeans associated with said timing means and connected to said trafllcresponsive 'means and operable by actuation of said trafllc responsivemeans'at said adjacent intersection to vary the time limit of saidtiming means at' said first mentioned intersection.

23. A trafiic control system including at one intersection ofinterfering trafllc lanes signalling means for according andinterrupting right of way in the lanes, trailic actuated means in thelanes of said intersection, operating means connected to said signallingmeans and trafllc actuated means to cause said signalling 'meanstotransfer right of way back and forth between the lanes in response toactuations of said trailic actu- 5 ated means, timing means associatedwith said operating means to provide time limits for the period of rightof way accorded to such lanes and including traflic responsive meanslocated at ad- Jacent intersections of traili'c lanes, each includingone lane common with the first mentioned intersection, and control meansassociated with said timing means and connected to said traflicresponsive means and including means operable by actuation of said tramcresponsive means at said adjacent intersections in each lane approachingsaid first mentioned intersection so as to tend to increase the timelimit of such lane and decrease the time limit on other lanes.

24. A trafiic control system for an intersection of trailic lanes"comprising signal means for according and interrupting right 01' way insuch lanes, a timer having an adjustable time setting and governing theoperation of said signal means normally to accord right of waycyclically to each 7 of said lanes in succession tor time periodsdetermined by such time setting, means for adjusting said time settingbetween certain limits to vary such right of way period betweencorresponding limits, traiilc responsive means in one of said lanes, andmeans connecting said adjusting means with said traffic responsive meansto operate the former progressively to vary said setting away from onelimit and toward the other upon successive actuations of the latter bytrafiic.

25. A traflic control system for the intersection of interfering tramclanes comprising signalling means adapted to accord and interrupt rightoi way to such lanes, a timer connected to and governing the operationof said signalling means normally to accord right of way cyclically andalternately to each of said lanes for time periods predetermined by itstime setting} trafic responsive means in each of said lanes foractuation by trafllc approaching the intersection, means forming a partof said timer and operating in response to successive actuations bytraflic in a first of said lanes to progressively adjust the time 5 in asecond of said lanes interfering with the first to progressively adjustthe time setting of said timer to decrease such time period for right ofway on said first lane from any time setting to which the timer has beenadjusted by the increase adjusting means.

HENRY A. HAUGH,- JR. CHARLES D. GEER. EUGENE D; S'IIRLEN.

CERTIFICATE OF CORRECTION.

Patent "No. 2,045,136. June 23, 1956.

HENRY A. HAUGH, JR. ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 4,first column, line 4, for "lircuit" read circuit; page 5, first column,line 4, for ""go" signal" read light; same page and column, strike outthe paragraph beginning with the word "While" comprising lines 49 to 65inclusive, and insert the same after line, 33, page 6, first column;page 5, second column, line 6, after "described" insert a .period; andline 73, for "light" read "go" signal; and that the said Letters Patentshould be read with these corrections therein that the same may conformto the record of the case in the Patent Office.

Signed and sealed this 22nd day of September, A. D. 1956.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

